The invention relates to a planar one-way clutch having a strut urged towards an engaging position by a spring.
Clutches are used in a wide variety of applications to selectively couple power from a first rotatable xe2x80x9cdrivingxe2x80x9d member, such as a driving disk or plate, to a second, independently-rotatable xe2x80x9cdrivenxe2x80x9d member, such as a driven disk or plate. In one known variety of clutches, commonly referred to as xe2x80x9cone-wayxe2x80x9d or xe2x80x9coverrunningxe2x80x9d clutches, the clutch xe2x80x9cengagesxe2x80x9d to mechanically couple the driving member to the driven member only when the driving member seeks to rotate in a first direction relative to the driven member. Once so engaged, the clutch will release or decouple the driven member from the driving member only when the driving member rotates in a second, opposite direction relative to the driven member. Further, the clutch otherwise permits the driving member to freely rotate in the second direction relative to the driven member. Such xe2x80x9cfree-wheelingxe2x80x9d of the driving member in the second direction relative to the driven member is also known as the xe2x80x9coverrunningxe2x80x9d condition.
One such known one-way clutch employs juxtaposed, nominally-coaxial driving and driven members featuring generally planar clutch faces in closely-spaced axial opposition. Such xe2x80x9cplanarxe2x80x9d one-way clutches, as taught by Frank in U.S. Pat. No. 5,449,057 and Ruth et al. in U.S. Pat. No. 5,597,057, typically include a plurality of recesses or xe2x80x9cpocketsxe2x80x9d formed in the face of the driving member and at least as many recesses or xe2x80x9cnotchesxe2x80x9d formed in the face of the driven member. A thin, flat pawl or strut, whose width is typically significantly less than its length, is carried within each of the driving member""s pockets such that a first longitudinal end of each strut may readily engage and bear against a radial shoulder defined by its respective pocket in the driving member. The strut""s second, opposite longitudinal end is urged towards and against the face of the driven member, for example, by a spring positioned in the pocket beneath the strut.
When the driving member rotates in the first direction relative to the driven member, the second end of at least one strut engages and thereafter bears against a radial shoulder defined by a notch in the driven member, whereupon the strut is placed in compression and the driven member is coupled for rotation with the driving member. When the driving member rotates in the second direction relative to the driven member, a ramped surface defined by other portions of the driven member""s notches urge the second end of each strut back towards the driving member, whereupon the driving member is permitted to freely rotate in the second direction relative to the driven member.
Typically, conventional springs, such as torsion springs, have been disposed under the struts to bias the struts into an engaging position. While these conventional springs have, for the most part, functioned in an acceptable manner, they have been somewhat susceptible to unwanted movement, especially radial and circumferential. Also, the types of spring that have been used in the past have necessitated relatively complex geometries in the driving member""s pockets, adding significant costs to the clutches. In addition to the above issues, these conventionally used springs have required significant care and costs to ensure proper assembly. Another possible disadvantage with the conventional springs is that they are relatively large, necessitating that the plate recesses that accommodate them be large. This may result in a possible diminishing of the part strength.
It would be desirable to provide a spring for use with one-way planar clutches which overcomes the above and other disadvantages with the conventionally used springs.
It is an object of the present invention to provide a one-way planar clutch, and a spring for use with the clutch, which overcomes the above discussed disadvantages in the prior art.
For carrying out the above, and other objects, the present invention provides a planar one-way clutch comprising a first plate and a second plate in close juxtaposed relationship with the first plate. Each plate is rotatable about a common axis. One of the plates is a driving plate and the other plate is a driven plate. Each plate has a coupling face and surfaces that define at least one recess in each respective coupling face. The recess in the first plate includes a strut receiving portion and a spring receiving portion.
At least one torque-transmitting strut is received within the strut receiving portion of the recess of the first plate. The strut is pivotable between a first position and a second position. The strut has a first end surface which is spaced from the surfaces defining the recess in second plate when the strut is in the first position. The first end surface of the strut engages at least one of the surfaces that defines the recess in the second plate when the strut is in the second position.
At least one spring is received within the spring receiving portion of the recess of the first plate. The spring has a base and an arm. The arm extends from the base and has a strut engaging portion which engages the strut and applies a controlled spring force on the strut to urge the strut toward the second position. The base of the spring is shaped so that portions of at least two diametrical surfaces are in engagement with the portions of diametrically opposed surfaces that define portions of the spring receiving portion of the recess of the first plate so that the spring base is in interference with a portion of the recess to prevent radial and circumferential movement of the spring relative to the spring receiving portion of the recess of the first plate. Preferably, the spring receiving portion of the recess in the first plate has a rectangular shape. Preferably, the recess is spaced axially in a plane which is below the strut.
In accordance with a feature of the present invention, the spring has a rectangular base that is defined by four segments. The base of the spring preferably includes an outer peripheral surface which continuously engages surfaces that define at least a portion of the spring receiving portion of the recess of the first plate to prevent rotational and lateral movement of the spring relative to the spring receiving portion of the recess of the first plate.
In accordance with another feature of the present invention, the base of the spring is defined by a pair of parallel legs and a single connector leg which extends essentially perpendicularly to the parallel legs and which connects the parallel legs. The base of the spring includes an outer surface which engages surfaces that define at least a portion of the spring receiving portion of the recess of the first plate to prevent rotational and lateral movement of the spring relative to the spring receiving portion of the recess of the first plate.
In accordance with yet another feature of the present invention, the base of the spring includes a pair of tabs, each of which extends laterally away from one of the parallel legs of the base of the spring. The tabs are bendable in an upward direction from the base and are able to be wrapped around a portion of the strut so that the tabs overly at least a portion of an upper side of the strut to secure the strut to the spring.
Although preferred embodiments of the invention are described and illustrated, the embodiments are not exclusive. Various modifications of the invention may be made without departing from the scope of the invention.